I agree with Nautigal about the strange phrasing. That "won't" feel like it should be a "will"?

I would reply as suggested asking why he cannot be tested (offering the option to correct what might be a typo) and saying that you look forward to meeting with the math specialist to learn how you can all help your child work "deeper".

I am having some of the same issues with DS6, so cheering for you and your child.